The present invention relates to conveyors, and more specifically, to diverter mechanisms for selectively diverting baggage, such as suitcases, from a first main belt conveyor onto an intersecting conveyor.
A variety of conveyor means having diverter mechanisms for transferring articles from a first main conveyor onto an intersecting conveyor have heretofore been developed. In particular, diverter assemblies have been developed for use with the following three types of conveyors: gravity powered conveyors, roller conveyors, and belt conveyors.
With gravity powered conveyors, articles normally move on top of a series of non-powered wheels, similar to roller skate wheels, as they move downhill along the conveyor. In a segment of the main conveyor, the wheels may be mounted on supports in such a manner that movement of the supports causes the wheels to become oriented diagonally with respect to the flow path of the main conveyor. When this occurs, an article moving along the conveyor will be diverted off toward a side of the main conveyor. lf an intersecting conveyor is located appropriately, the article will be diverted thereto.
In a variation on this type of diverter, the wheels are mounted permanently angled with respect to the flow path of the main conveyor and are recessed below the main conveyor surface and do not engage the articles, when the articles are not intended to be diverted. Then, when diversion is desired, the wheels are raised partially above the surface of the conveyor so that an article traveling down the main conveyor will engage them and will be lifted and diverted to the side.
In a powered roller conveyor, articles rest on top of the rollers and are conveyed as the rollers are rotated by a power source. A powered roller conveyor comprises a plurality of these powered rollers aligned parallel to one another. A diverter for such a conveyor is normally located in a gap where one or more of these rollers have been removed. In most instances, the diverters operate similarly to those above noted for gravity conveyors. Additionally, diverters in which the diverter rollers are themselves powered are known.
In belt conveyors, the articles are transported on an upper surface of a continuous belt, the belt being supported by or driven by powered rollers. Diverter assemblies for belt conveyors present special problems, since something must be done with the belt as it passes the gap in the main conveyor where the diverter assembly is located. Normally, the belt is detoured about that gap by rollers located beneath a conveying level of the main belt conveyor.
One major type of diverter for belt conveyors has diverter rollers which are permanently mounted at an angle to the main conveyor and are supported by a mechanism which raises and lowers them with respect to the level of article movement along the conveyor. When these permanently angled rollers are raised, articles moving along the main belt conveyor will encounter them and be lifted and angled toward an intersecting second conveyor. When they are lowered, they are below the level of article movement and do not engage the articles. Normally, these rollers are powered to impart momentum to the articles as they are driven toward the secondary conveyor.
Numerous problems have been associated with these types of conveyor diverters, particularly when they are used in belt conveyors. While belt conveyors can be very safe and efficient, the large belts are massive and can require constant support and power for their operation. Accordingly, when a gap is made in the main conveyor for the location of a diverter assembly, it is desirable that the space be as small as possible to avoid any extended area over which the belt is not supported and powered. Additionally, since the belt must be diverted about the gap, a shallow depth of diverter assembly is desirable, again, so that the belt is unsupported and unpowered over the smallest possible gap.
Another reason for a small gap is so that when articles conveyed by the belt conveyor are not being diverted, they pass unsupported and unpowered over the smallest area of conveyor possible. Minimizing the size of the gap also reduces the amount of vibrational shock transmitted to the article as it passes the diverter, thus decreasing the likelihood of causing damage to the baggage while at the same time increasing operating speed. Additionally, many bags have projections which can fall into, and become caught in, larger gaps, thereby stopping the conveyor system or damaging the articles. Finally, in baggage conveyors, packages and bags of many different sizes pass over the diverter and a smaller gap accommodates them more efficiently.
In the past, there have been two basic sources of problems with the size of the gap in these types of diverters. First, when the diverter rollers are mounted at an angle, they generate a need for a wider gap, if the rollers are of substantial axial length, since the pivoting causes the rollers to take up more room in the direction of the width of the gap. Rollers of greater axial length, however, are preferred, for efficiency in imparting momentum to the articles and in supporting the articles. Additionally, when the rollers are recessed, when not in use diverting articles, an article moving along the main conveyor must pass completely over the gap, receiving no support from the recessed rollers. This means only larger articles can be conveyed.
In another type of powered diverter, the diverter rollers are mounted at a permanent vertical position slightly above the conveying surface of the main conveyor. When diversion is desired, the rollers are pivoted toward the side. Articles moving along the main conveyor, then, are raised by the diverter rollers and are diverted. A major problem with this type of diverter is that even when diversion is not desired, the articles bump into, and are raised by, the diverter rollers. This imparts unnecessary and sometimes damaging shock to the articles.
In powered conveyors, the diverter rollers of the diverter assembly are preferably raised slightly above the conveying surface of the main conveyor, so that they lift the article slightly, and remove the component of momentum imparted by the main conveyor, as the article is diverted. The diverter rollers are preferably rotationally powered, for efficiency in diverting the articles from their original course. In fact, it has been found that if the surface speed of the diverter rollers is not greater than that of the main conveyor, the pieces of baggage will tend to bunch up, and collide, at the diverter assembly. This is particularly true if the angle of diversion is great; and larger angles of diversion are preferable, since they cause the article to be diverted more rapidly, and over a shorter turn distance, than do small angles.
Two methods of powering diverter rollers are generally available. These are: with power mechanically derived from the main conveyor, and with power mechanically derived from an independent motor. In the past, there have been problems with both of these. In the first, it has often been found that the main conveyor bogs down from the drag placed upon it, either when the diverter rollers are themselves clutched into the system, or when a heavy load is placed upon those diverter rollers and more power is needed to drive them. In the case of the independently powered rollers, while the clutch-in problem may be solved somewhat, the extra power supply may take up valuable space, create economic inefficiencies, and add more moving parts, and therefore higher risk of failure, to an already complex mechanical system.
Finally, a conveyor diverter, for use with airport baggage, must be made particularly durable in order to survive the rigorous continuous use to which it will be put.